Some experimentiing with a cheap PAM8403 Class D Audio Amplifier Module results in a very compact and efficient stereo amp with very reasonable sound quality.
Eight 1-watt LEDS, a couple of cheap eBay modules, some salvaged hardware, and an ATTINY13 make for some very effective workbench lighting. A speed-controlled fan keeps the electronics and LEDs (and potentially the worker) cool.
A command line utilty that allows a Raspberry Pi to control a HD44780 based LCD via i2c.
A Raspberry Pi, USB hub and USB HDD are mounted in a box to make a neat little low-power server. Runs from a 12v battery charged by solar power. Uses around 6W as compared to 30W or more of the laptop that it replaces.
A utility to monitor a Sunny Boy 4000tl solar inverter via its Bluetooth interface. Uses a cheap tl-wr702n wireless router, but should work with any Linux system and with other Sunny Boy inverters.
A quick-start guide to getting a cross compilation environment up and running on Ubuntu Linux.
This replacement thermostat for an old refrigerator offers LCD display showing temperature in C or F, 0.5C accuracy and allows target temperature to be set percisely. Uses ATmega8 controller and DS18B20 1-wire sensor.
Made by bending a coat hanger, this antenna is for 70cm and can be scaled for UHF CB. It works well, especially considering how quick and easy it is to make.
An interactive map showing Australian amateur radio repeaters. Navigate as required and click on a repeater-site icon to display frequency, ctcss and other details and notes. Display all repeaters or select by band.
The concepts behind direct digital synthesis (DDS) can be explained without the need for complex maths nor heavy-duty digital electronics theory. This tutorial describes how DDS works in simple and easy to understand terms.
A minimalist DIY programming and development board for the ATtiny2313 AVR microcontroller. Made on a piece of matrix board using point-to-point wiring.
A half-wave end-fed for 2m is built from PVC pipe and a couple of meters of RG58 coax. This easily reproducible design from VK2ZOI can be made quickly and performs well. The addition of some tinfoil and sticky tape turns this into a dual-band 70cm collinear.